<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <meta http-equiv="X-UA-Compatible" content="ie=edge">
    <title>Document</title>
</head>
<body>
    <input type="button" value="hello" id="test">
    <script>
    var value="change"
    var test=document.getElementById("test");
    test.onclick=function(){
        // settimerout(function(){
            // console.log(this.value);
        // },300)
         go();/* this还是指向window-->函数正常调用，this指向window */
    }
    function go(){
        console.log(this.value);
    }
    </script>
</body>
</html>